2. On a New Variety of Ocular Spectrum

Abstract

If we look for a short time at any object, and afterwards turn the eye in another direction, we see a spectral image of the form of the object first looked at.Again, if after we have looked at any coloured object we turn the eye in another direction, we see a spectral image of a colour complimentary to that first looked at.In addition to these spectral forms and colours, I find there is another and distinct kind of ocular spectrum, which we may call a motion spectrum. It is seen when we look first at a body in motion and afterwards direct the eye towards an object at rest. The object at rest, when seen under these conditions, seems to be in motion, and the direction of its apparent motion is the opposite of that of the moving body first looked at.